British Pat. No. 2,062,475 B discloses a pneumatic control system for an anaesthesia respiratory apparatus in which a switchover from automatic respiration to manual respiration and vice versa can be performed by means of a multiple-position valve. For this purpose, the two valves are switched in alternation via an appropriate charge of pressure on the control chamber of the one valve, and the two diaphragm seals of the valves are connected with one another via a common strut. If one valve is open, the other valve is closed, and vice versa. In the pressure chamber of the second valve there is a compression spring, which keeps the diaphragm associated therewith closed as long as no suitable pressure is present in the pressure chamber of the first valve. This kind of valve combination comprises a multiplicity of individual parts, which require a complicated structure and which, when a required cleaning or disinfection of the individual parts that come into contact with respirating gas is performed, necessitate a tedious disassembly and reassembly of these parts.
A further kind of respiratory apparatus is described in published German Patent Application DE-OS No. 33 03 998. Although here a separation between an electronically operating control part and groups of parts that carry respirating gas is sought, nevertheless here again the many valves required are embodied as individual assemblies, and each with all its parts must be dissassembled and assembled again for cleaning purposes.